The conventional manila paper file folder has been in use for decades. It is fabricated from a single sheet of manila paper which is cut and folded to provide front and rear panels hinged together along one edge. Usually, the rear panel is provided with a tab for indexing purposes.
While the conventional folder may function satisfactorily for its intended purpose, it has certain limitations. For instance, the opacity of the front panel prevents anything contained within the folder from being viewed from the front. As a result, information about the contents of the file is usually placed on the tab. However, due to the size and space limitations of the tab, only a limited amount of information can be recorded. It would be more desirable for an index sheet to be placed in the front of the file and the folder designed so that the index sheet or folder contents can be viewed through the front panel.
All-plastic folders having transparent front and rear panels are known. While these folders overcome some of the limitations of manila folders, they have other limitations. For instance, all-plastic folders lack the desired structural integrity, i.e. rigidity, which is an important requirement for a desirable file folder. All-plastic folders are more expensive to manufacture than manila folders because plastic is more expensive than paper. Also, all-plastic folders are more difficult to decorate with printing, and they do not allow index or other notations to be applied with as wide a variety of writing implements as do manila folders. Moreover, since all-plastic folders have hard crease hinge lines, it is difficult for them to be laid flat in open position without overstressing their hinge line, and repeated overstressing of the hinge line is likely to cause premature failure.